Magnetocaloric module for magnetic refrigeration apparatus

ABSTRACT

A magnetocaloric module for a magnetic refrigeration apparatus includes: a bed having an inner surface; a magnetocaloric material filled in the bed; and an insulating layer formed over the inner surface, isolating the magnetocaloric material from the bed. With the use of the insulating layer, thermal conduction between the magnetocaloric material and the bed can be reduced and Galvanic corrosion which may occur to the bed can be prevented. Also, a temperature gradient of the magnetocaloric module may be further extended.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to magnetic refrigeration techniques, and in particularly to a magnetocaloric module for a magnetic refrigeration apparatus.

2. Description of the Related Art

At present, almost all refrigeration technologies applied in an environment of room temperature, which is closely associated with the daily lives of humans, for example, a refrigerator, a freezing chamber, a room heating/cooling system, and the like, mostly employ a gas compression/expansion cycle. However, the refrigeration technologies based on the gas compression/expansion cycle have a serious problem of environmental destruction due to specific freon gas discharged into the environment. Further, as to an alternative freon gas, its adverse affects on the environment are also of concern.

Thus, expectations have been raised for magnetic refrigeration technologies using a magnetocaloric effect as one of the environmentally conscious and effective refrigeration technology. Accordingly, the speed of research and development for magnetic refrigeration technologies for room temperature environments have been accelerated.

A conventional magnetic refrigeration apparatus is disclosed in U. S. Pat. App. Pub. No. 2010/0058775. As shown in FIG. 1, the magnetic refrigeration apparatus comprises an active magnetic regenerative refrigeration (AMR) bed 10 filled with magnetic materials 12 with magnetocaloric effect, a horizontally movable permanent magnet 14 disposed to the outside of the AMR bed 10 as a magnetic field generation device, a low temperature side heat exchanging unit 21, a high temperature side heat exchanging unit 31, a switching means 40. Also, a refrigerant pump 50.

The magnetic refrigeration apparatus shown in FIG. 1 uses, for example, water as the liquid refrigerant. The low temperature side heat exchanging unit 21 is disposed to a low temperature end side of the AMR bed 10, and the high temperature side heat exchanging unit 31 is disposed to a high temperature end side of the same. The switching means 40 is interposed between the low temperature side heat exchanging unit 21 and the high temperature side heat exchanging unit 31 to switch a refrigerant flow direction. The refrigerant pump 50 is connected to the switching means 40 as a refrigerant transport means. Then, the AMR bed 10, the low temperature side heat exchanging unit 21, the switching means 40, and the high temperature side heat exchanging unit 31 are connected to each other through a pipe to thereby form a refrigerant flow path for circulating the liquid refrigerant.

During operation of the magnetic refrigeration apparatus shown in FIG. 1. the permanent magnet 14 is disposed to a position confronting the AMR bed 10 (position shown in FIG. 1), to apply a magnetic field to the magnetic material 12 in the AMR bed 10. Therefore, the magnetic material 12 having the magnetocaloric effect generates heat. Accordingly, the liquid refrigerant is circulated by the operations of the refrigerant pump 50 and the switching means 40 in a direction from the AMR bed 10 to the high temperature side heat exchanging unit 31. Heat is transported to the high temperature side heat exchanging unit 31 by the liquid refrigerant, wherein the temperature of the liquid refrigerant is increased by the heat generated by the magnetic material 12.

Thereafter, the permanent magnet 14 is moved from the position confronting the AMR bed 10, and the magnetic field applied to the magnetic material 12 is removed. The magnetic material 12 absorbs heat by removing the magnetic field. Accordingly, the liquid refrigerant is circulated by the operations of the refrigerant pump 50 and the switching means 40 in a direction from the AMR bed 10 to the low temperature side heat exchanging unit 21. A cooler temperature is transported to the low temperature side heat exchanging unit 21 by the liquid refrigerant cooled by the heat absorption of the magnetic material 12.

A temperature gradient is formed in the magnetic material 12 in the AMR bed 10 by repeating the application and removal of the magnetic field to and from the magnetic material 12 in the AMR bed 10 by repeating the movement of the permanent magnet 14. Then, the low temperature side heat exchanging unit 21 is continuously cooled by moving the liquid refrigerant in synchronization with the application and the removal of the magnetic field.

However, due to physical connections between the magnetic material 12 and the AMR bed 10, and different metal materials of the magnetic material 12 and the AMR bed 10, thermal dissipation and Galvanic corrosion may be caused to the AMR beds 10, thereby affecting thermal and physical reliabilities of the magnetic refrigeration apparatus comprising the AMR bed 10.

BRIEF SUMMARY OF THE INVENTION

Accordingly, a magnetocaloric module for a magnetic refrigeration apparatus with reduced thermal dissipation and Galvanic corrosion is provided.

An exemplary magnetocaloric module for a magnetic refrigeration apparatus comprises a bed having an inner surface; a magnetocaloric material filled in the bed; and an insulating layer formed over the inner surface, isolating the magnetocaloric material from the bed. With the use of the insulating layer, thermal conduction between the magnetocaloric material and the bed can be reduced and Galvanic corrosion which may occur to the bed can be prevented. Also, a temperature gradient of the magnetocaloric module may be further extended.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is schematic diagram showing a conventional magnetic refrigeration apparatus;

FIG. 2 is a magnetocaloric module according to an embodiment of the invention;

FIG. 3 is a magnetocaloric module according to another embodiment of the invention;

FIG. 4 is a magnetocaloric module according to yet another embodiment of the invention;

FIG. 5 is a magnetocaloric module according to another embodiment of the invention;

FIG. 6 is a magnetocaloric module according to yet another embodiment of the invention; and

FIG. 7 is a magnetocaloric module according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.

FIGS. 2-7 are various embodiments respectively showing a magnetocaloric module with reduced thermal dissipation and Galvanic corrosion issues, wherein the magnetocaloric module shown in FIGS. 2-7 may be capable to function as, for example, the active magnetic regenerative refrigeration (AMR) bed 10 of the magnetic refrigeration apparatus shown in FIG. 1.

In FIG. 2, an exemplary magnetocaloric module A is illustrated. comprising a bed 100. Also, a plurality of magnetic particles 102 and an insulating layer 104 formed in the bed 100. The bed 100 is formed with opposing two ends 150 and 160 such that a heat transfer fluid is allowed, for example water, to flow through spaces 108 between the magnetic particles 102 to transfer heat between a low temperature end (one of the ends 150 and 160) and a high temperature end (the other one of the ends 150 and 160) of the bed 100 during operation of a magnetic refrigeration apparatus (not shown) comprising the magnetocaloric module A.

In the magnetocaloric module A shown in FIG. 2, the insulating layer 104 formed in the bed 100 entirely covers an inner surface 110 of the bed 100 and isolates the magnetic particles 102 from the bed 100. Therefore, thermal conduction between the magnetic particle 102 and the bed 100 can be reduced and Galvanic corrosion which may occur to the bed 100 can be prevented due to formation of the insulating layer 104. Also, a temperature gradient of the magnetocaloric module A during operation may be further extended. The insulating layer 104 in FIG. 2 is formed as a single layer and comprises only a kind of insulating material.

In FIG. 3, another exemplary magnetocaloric module B is illustrated, and the insulating layer 104 provided in the bed 100 of the magnetocaloric module B is now composed of two insulating sub-layers 104 a and 104 b made of different materials. Other components of the magnetocaloric module B is the same as that of the magnetocaloric module A shown in FIG. 2 and are not described here for simplicity. As shown in FIG. 3, the first insulating sub-layer 104 a and the second insulating sub-layer 104 b respectively covers a different portion of an inner surface 110 of the bed 100, and the insulating layer 104 is a composite insulating layer entirely covering the inner surface 110 of the bed 100 and isolating the magnetic particles 102 from the bed 100. Therefore, thermal conduction between the magnetic particle 102 and the bed 100 can be reduced and Galvanic corrosion which may occur to the bed 100 can be prevented due to formation of the first and second sub-layers 104 a and 104 b of the insulating layer 104. Also, a temperature gradient of the magnetocaloric module B during operation may be further extended.

In FIG. 4, yet another exemplary magnetocaloric module C is illustrated, and the insulating layer 104 provided in the bed 100 of the magnetocaloric module C is now composed of two insulating layers 104 c and 104 d made of different materials. Other components of the magnetocaloric module C is the same as that of the magnetocaloric module A shown in FIG. 2 and are not described here for simplicity. As shown in FIG. 4, the insulating layer 104 c entirely covers an inner surface 110 of the bed 100, and the insulating layer 104 d entirely covers a surface (not shown) of the insulating layer 104 c. The insulating layer 104 is a composite insulating layer comprising the insulating layers 104 c and 104 d, and isolating the magnetic particles 102 from the bed 100. Therefore, thermal conduction between the magnetic particle 102 and the bed 100 can be reduced and Galvanic corrosion which may occur to the bed 100 can be prevented due to formation of the first and second insulating layers 104 c and 104 d of the insulating layer 104. Also, a temperature gradient of the magnetocaloric module C during operation may be further extended.

In FIG. 5, another exemplary magnetocaloric module A′ is illustrated, and the insulating layer 104 provided in the bed 100 of the magnetocaloric module A′ partially covers an inner surface 110 of the bed 100. Other components of the magnetocaloric module B is the same as that of the magnetocaloric module A shown in FIG. 2 and are not described here for simplicity. As shown in FIG. 5, the insulating layer 104 formed in the bed 100 partially covers an inner surface 110 of the bed 100 and isolates the magnetic particles 102 from most portions of the bed 100. In this embodiment, a portion of about 0-50% of the inner surface 110 of the bed 100 is exposed, such that thermal conduction between the magnetic particle 102 and the bed 100 can still be reduced and Galvanic corrosion which may occur to the bed 100 can still be reduced due to formation of the insulating layer 104. Preferably, the portion of about 10-45% of the inner surface 110 of the bed 100 is exposed. Therefore, a temperature gradient of the magnetocaloric module A′ during operation may be further extended. The insulating layer 104 in FIG. 5 is formed as a single layer and comprises only a kind of insulating material.

In FIG. 6, yet another exemplary magnetocaloric module B′ is illustrated, and the insulating layer 104 provided in the bed 100 of the magnetocaloric module B′ is now composed of two insulating sub-layers 104 a and 104 b made of different materials. Other components of the magnetocaloric module B is the same as that of the magnetocaloric module A shown in FIG. 3 and are not described here for simplicity. As shown in FIG. 6, the first insulating sub-layer 104 a and the second insulating sub-layer 104 b respectively covers a different portion of an inner surface 110 of the bed 100, and isolates the magnetic particles 102 from most portions of the bed 100. The second insulating sub-layer 104 b partially exposes a portion of the inner surface 110 of the bed 100. Also, a portion of about 0-50% of the inner surface 110 of the bed 100 is exposed, such that thermal conduction between the magnetic particle 102 and the bed 100 can still be reduced and Galvanic corrosion which may occur to the bed 100 can still be reduced due to formation of the insulating layer 104. Preferably, the portion of about 10-45% of the inner surface 110 of the bed 100 is exposed. Therefore, a temperature gradient of the magnetocaloric module B′ during operation may be further extended.

In FIG. 7, another exemplary magnetocaloric module C′ is illustrated, and the insulating layer 104 provided in the bed 100 of the magnetocaloric module C′ is now composed of two insulating layers 104 c and 104 d made of different materials. Other components of the magnetocaloric module C is the same as that of the magnetocaloric module A shown in FIG. 4 and are not described here for simplicity. As shown in FIG. 7, the insulating layer 104 c covers most portions of an inner surface 110 of the bed 100 and exposes a portion of the inner surface 110 of the bed, and the insulating layer 104 d entirely covers a surface (not shown) of the insulating layer 104 c. In this embodiment, a portion of about 0-50% of the inner surface 110 of the bed 100 is exposed, and the insulating layer 104 is a composite insulating layer comprising the insulating layers 104 c and 104 d to isolate the magnetic particles 102 from most portions of the bed 100. Therefore, thermal conduction between the magnetic particle 102 and the bed 100 can still be reduced and Galvanic corrosion which may occur to the bed 100 can be reduced due to formation of the first and second insulating layers 104 c and 104 d of the insulating layer 104. Preferably, the portion of about 10-45% of the inner surface 110 of the bed 100 is exposed. Therefore, a temperature gradient of the magnetocaloric module C′ during operation may be further extended.

In the various embodiments as disclosed in FIGS. 2-7, in addition to the advantages such as the reduction of thermal conduction and Galvanic corrosion as described above, the insulating layer 104, or the insulating sub-layers 104 a and 104 b, or the first and second insulting layers 104 c and 104 d provided in the bed 100 may further reduce spaces 108 between the magnetic particles 102 to thereby enhance a heat exchange efficiency of the magnetocaloric module. Moreover, the bed 100 can be formed in any shape, for example, a rectangular shape, cylindrical shape, or other polygonal shapes, and may comprise magnetic permeable materials such as steels or irons. The steels can be, for example, STEEL 1004, STEEL 1008, STEEL 1010, STEEL 1002, or SS41, and the irons can be, for example, electrical pure iron (DT4). The insulating layer 104, or the insulating sub-layers 104 a and 104 b, or the first and second insulting layers 104 c and 104 d may comprise foamed materials, silica gel, rubber, or gas-filled foamed materials, or latexes. The magnetic particles 102 may comprise magneto-caloric materials, such as FeRh, Gd₅Si₂Ge₂, Gd₅(Si_(1-x)Ge_(x))₄, RCo₂, La(Fe_(13-x)Si_(x)), MnAs_(1-x)Sb_(x), MnFe(P, As), MnFe(P, Co(S_(1-x)Se_(x))₂, NiMnSn, MnCoGeB, R_(1-x)M_(x)MnO₃, (where R=lanthanide, M=Ca, Sr and Ba), . . . etc. The magnetic particles 102 may be formed in other configurations such as a mesh-like, flake-like, tube-like, rod-like, sheet-like and honeycomb-like configuration, and is not limited to the particle-like configuration.

Note that for all embodiments mentioned above, additives for enhancing performance could be added into the fluid pathway (e.g. a fluid pathway between the two ends 150 and 160 of the bed 100), such as a dispersant, an anti-corrosion agent, an antifreeze agent, or a drag-reduction agent. The dispersant (or dispersing agent, or plasticizer, or super-plasticizer as Wikipedia™ disclosed) is either a non-surface active polymer or a surface-active substance added to a suspension, usually a colloid, to improve the separation of particles and to prevent settling or clumping. Dispersants consist normally of one or more surfactants, but may also be gases. The anti-corrosion agent (or corrosion inhibitor) is used for preventing magnetocaloric material (particles) from corrosion or erosion after cycles of fluid passing thereby. The antifreeze agent (or anti-frozen agent) is used to prevent the working fluid from freezing in some cooling processes. The drag-reduction agent (or flow improver as Wikipedia™ disclosed) is a long chain polymer chemical that is used in crude oil, refined products or non-potable water pipelines. It is injected in small amounts (parts per million) and is used to reduce the frictional pressure which drops along the pipeline's length.

While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

What is claimed is:
 1. A magnetocaloric module for a magnetic refrigeration apparatus, comprising: a bed having an inner surface; a magnetocaloric material filled in the bed; and an insulating layer formed over the inner surface, isolating the magnetocaloric material from the bed.
 2. The magnetocaloric module as claimed in claim 1, wherein the insulating layer entirely covers the inner surface of the bed and the magnetocaloric material fails to contact the inner surface of the bed.
 3. The magnetocaloric module as claimed in claim 2, wherein the insulating layer is a single layer.
 4. The magnetocaloric module as claimed in claim 2, wherein the insulating layer is a composite layer comprising a first insulating sub-layer and a second insulating sub-layer, and the first insulating sub-layer and the second insulating sub-layer respectively covers a different portion of the inner surface of the bed.
 5. The magnetocaloric module as claimed in claim 2, wherein the insulating layer is a composite layer comprising a first insulating layer and a second insulating layer, and the first insulating layer entirely covers the inner surface of the bed and the second insulating layer entirely covers a surface of the first insulating layer.
 6. The magnetocaloric module as claimed in claim 1, wherein the insulating layer covers most of the inner surface of the bed and a portion of about 0-50% of the inner surface of the bed is exposed such that the magnetocaloric material partially contacts the inner surface of the bed.
 7. The magnetocaloric module as claimed in claim 1, wherein the insulating layer covers most of the inner surface of the bed and a portion of about 10-45% of the inner surface of the bed is exposed such that the magnetocaloric material partially contacts the inner surface of the bed.
 8. The magnetocaloric module as claimed in claim 6, wherein the insulating layer is a single layer.
 9. The magnetocaloric module as claimed in claim 6, wherein the insulating layer is a composite layer comprising a first insulating sub-layer and a second insulating sub-layer, and one of the first insulating sub-layer and the second insulating sub-layer exposes the portion of the inner surface of the bed.
 10. The magnetocaloric module as claimed in claim 6, wherein the insulating layer is a composite layer comprising a first insulating layer and a second insulating layer, and the first insulating layer partially covers the inner surface of the bed and the second insulating layer entirely covers a surface of the first insulating layer.
 11. The magnetocaloric module as claimed in claim 1, wherein the bed comprises magnetic permeable materials.
 12. The magnetocaloric module as claimed in claim 11, wherein the magnetic permeable materials comprise steels or irons.
 13. The magnetocaloric module as claimed in claim 1, wherein the bed is formed with a shape selected from a group consisting of a rectangular shape, cylindrical shape, and polygonal shape.
 14. The magnetocaloric module as claimed in claim 1, wherein the insulating layer comprise foamed materials, silica gel, rubber, or gas-filled foamed materials, or latexes.
 15. The magnetocaloric module as claimed in claim 1, wherein the magnetocaloric material comprises FeRh, Gd₅Si₂Ge₂, Gd₅(Si_(1-x)Ge_(x))₄, RCo₂, La(Fe_(13-x)Si_(x)), MnAs_(1-x)Sb_(x), MnFe(P, As), MnFe(P, Si), Co(S_(1-x)Se_(x))₂, NiMnSn, MnCoGeB, or R_(1-x)M_(x)MnO₃, (where R=lanthanide, M=Ca, Sr and Ba).
 16. The magnetocaloric module as claimed in claim 1, wherein the magnetocaloric material is formed in a configuration selected from a group consisting of a particle-like, mesh-like, flake-like, tube-like, rod-like, sheet-like and honeycomb-like configuration. 